Porous silicon is a form of silicon material that has holes (pores) in small scales. According to existing nomenclature, adopted by the International Union of Pure and Applied Chemistry (IUPAC), there can be three categories of pores with regard to the pore dimensions: microspores, mesopores, and macrospores with average pore diameters of less than 2 nm, 20-50 nm, and greater than 50 nm, respectively. The pores in porous silicon can also display various morphologies, i.e. shape, orientation, alignment, and interconnection of pores, among others.
Porous silicon is a dielectric material with applications in a wide range of areas. Previous and ongoing research on the application of porous silicon can be found in, among others, optoelectronics, micro-optics, energy conversion, environmental monitoring, microelectronics, wafer technology, micromachining, and biotechnology.